Authors/Ockham/Summa Logicae/Book III-1/Chapter 2

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Latin English
[Cap. 2 De quibusdam praeambulis quae praemittenda sunt antequam descendatur ad propositum] [Of certain preliminaries which we should give first, before we go to the matter in hand]
Positis divisionibus et distinctionibus syllogismi, de quibusdam dividentibus in speciali est dicendum. Et primo de uniformi generatione syllogismorum de inesse, secundo de uniformi modalium, et tertio de mixtis. Having given the divisions and distinctions of the syllogism, we should speak of certain specific divisions. And first, of the uniform generation of assertoric syllogisms, second, of the uniform generation of modal syllogisms, and third, of mixed syllogisms.
Circa primum primo est dicendum de syllogismis ex omnibus de inesse et de praesenti, secundo de aliis. Sed antequam accedatur ad propositum, videnda sunt quaedam praeambula. Concerning the first, we should speak about syllogism from propositions that are all assertoric and present tense, second, of others. But before we reach the matter in hand, we should deal with certain preliminaries.
Primum est quod tantum sunt duae praemissae categoricae ponendae in syllogismo et conclusio; et tantum tres termini, scilicet maior extremitas et minor et medium. Est autem medium quod ponitur in utraque praemissa; maior extremitas est quae cum medio termino ponitur in maiori; minor extremitas quae ponitur cum medio in minori propositione, hoc est in secunda propositione. The first is that in a syllogism there are only two categorical premisses plus a conclusion, and only three terms , namely the major, the minor and the middle term. Now the middle is the term given in both premisses, the major is the term which is given with the middle term in the major premiss, the minor term is the term which is given with the middle in the minor premiss (i.e. the second proposition)
Secundum est quod tantum sunt tres figurae. Prima est in qua medius terminus subicitur in prima propositione et praedicatur in secunda. Secunda figura est quando medius terminus praedicatur in utraque. Tertia figura est quando medius terminus subicitur in utraque. Non est apponenda quarta figura, quia si medius terminus praedicetur in prima propositione et subiciatur in secunda, non erit nisi transpositio propositionum positarum in prima figura, et ideo non sequitur alia conclusio quam illa quae sequitur ex praemissis dispositis in prima figura. The second is that there are only three figures. The first is in which the middle term is the subject in the first premiss, and the predicate in the second. The second figure is when the middle term is predicated in both. The third figure is when the middle term is the subject in both. There is no fourth figure to be added, for if the middle term is the predicate in the first proposition and the subject in the second, it will only be a transposition of the propositions given in the first figure, and therefore there will not follow any other conclusion than that which follows from the premisses arranged in the first figure.
Et ideo non est negandum quin possit argui ex duabus praemissis in quarum prima medius terminus praedicetur et in secunda subiciatur, sed illa conclusio quae primo sequitur ex illis praemissis erit eadem quae sequitur ex eisdem praemissis dispositis in prima figura. Si enim arguatur sic 'omnis homo est animal; omne animal est substantia', conclusio quae primo sequitur est ista 'igitur omnis homo est substantia'. Et ista sequitur ex praemissis eisdem, dispositis in prima figura, sic 'omne animal est substantia omnis homo est animal; igitur omnis homo est substantia'. And therefore it should not be denied but that it could be argued from the two premisses, in the first of which the middle term is the predicate and in the second the subject, but the conclusion which first follows from those premisses will be the same as from the same premisses arranged in the first figure. For if we argue "every man is an animal, every animal is a substance", the conclusion which follows first is "therefore every man is a substance". And this follows from the same premisses arranged as in the first figure, thus: "every animal is a substance, every man is an animal, therefore every man is a substance".
Tertium praeambulum est quod omnis syllogismus, immediate vel mediate, regulatur per dici de omni vel per dici de nullo. Syllogismi enim in prima figura regulantur immediate per dici de omni vel per dici de nullo. Syllogismi autem secundae et tertiae figurae reducuntur in syllogismos primae figurae, vel per conversionem vel per impossibile vel per transpositionem propositionum, et ideo mediate regulantur per dici de omni vel per dici de nullo. Et quandocumque sic est quod aliquis discursus regulatur per dici de omni vel per dici de nullo, sive mediate sive immediate, ille discursus est bonus. The third preliminary is that every syllogism, immediate or mediate, is governed by dici de omni or dici de nullo. For syllogisms in the first figure are governed immediately by dici de omni, or by dici de nullo. And syllogisms of the second and third figure are reduced into syllogisms of the first figure, either by conversion or per impossible or by the transposition of propositions, and are therefore mediately governed by dici de omni or dici de nullo. And whenever it is the case that some discourse is governed by dici de omni or dici de nullo, whether mediately or immediately, that discourse is good.
Est autem dici de omni quando nihil est sumere sub subiecto, quin de eo dicatur praedicatum,. Quod est sic intelligendum: non quod praedicatum conveniat cuilibet de quo dicitur subiectum, -- tunc enim non esset dici de omni nisi in propositionibus veris --, sed sufficit quod per talem propositionem denotetur quod nihil sit sumere sub subiecto, quin de eo dicatur praedicatum. Et hoc denotatur per omnem propositionem universalem affirmativam. Dici de nullo est quando per eam denotatur quod de quocumque dicitur subiectum, quod ab eo removetur praedicatum. Et hoc denotatur per omnem propositionem universalem negativam, sive sit vera sive falsa. Now dici de omni happens when nothing is subsumed under the subject, without the predicate being predicated of it, which is to be understood as follows. Not that the predicate belongs to everything of which the subject is predicated (for then it would only be dici de omni in true propositions), but that it is sufficient that by such a proposition it is denoted that nothing is subsumed under the subject, without the predicate being predicated of it. And this is denoted by every universal affirmative proposition. Dici de nullo is when it is denoted by the proposition that whatever the subject is predicated of, the predicate is removed from it. And this is denoted by every universal negative proposition, whether it is true or false.

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